在python中水平对齐条形图的图例

Question

我使用以下代码制作了多轴图形，并且无法按照我的需要安排图例。我图的代码如下：

import matplotlib.pyplot as plt 
import numpy as np 

x = np.arange(4) 

y = [5, 7, 4, 9] 
z = [9, 3, 5, 6] 
r = [30, 40, 45, 37] 


fig,ax = plt.subplots() 

abc = ax.bar(x,y,0.25) 
cde = ax.bar(x+0.25,z,0.25) 

ax.legend((abc[0], cde[0]), ('y', 'z'),bbox_to_anchor=(0., 1.02, 1, .102) , borderaxespad=0.) 
ax.set_xticks(x + 0.25/2) 
ax.set_xticklabels(('A', 'B', 'C', 'D')) 

ax2 = ax.twinx() 
efg = ax2.plot(x+0.25/2,r,color = 'black',label = "r") 
ax2.legend(bbox_to_anchor=(0.11,1.07) , borderaxespad=0.) 

plt.show() 

它显示的图是这样的。

右上角的图例垂直对齐，但我希望它们水平对齐。我找不到任何文件。我希望它们如下图所示。

感谢

Answer 1

您需要使用ncol的说法，这将列数在legend使用，例如ncol=2会给你两列。

ax.legend(..., ncol=2) 

然后你可以看一下how to place the legend一起使用loc参数与bbox_to_anchor，找到合理的参数，使双方的传说彼此对齐：

import matplotlib.pyplot as plt 
import numpy as np 

x = np.arange(4) 

y = [5, 7, 4, 9] 
z = [9, 3, 5, 6] 
r = [30, 40, 45, 37] 


fig,ax = plt.subplots() 

abc = ax.bar(x,y,0.25) 
cde = ax.bar(x+0.25,z,0.25) 

ax.legend((abc[0], cde[0]), ('y', 'z'),loc="lower right", bbox_to_anchor=(1., 1.02) , borderaxespad=0., ncol=2) 
ax.set_xticks(x + 0.25/2) 
ax.set_xticklabels(('A', 'B', 'C', 'D')) 

ax2 = ax.twinx() 
efg = ax2.plot(x+0.25/2,r,color = 'black',label = "r") 
ax2.legend(bbox_to_anchor=(0,1.02),loc="lower left", borderaxespad=0.) 

plt.show()